Question

The value of y is inversely proportional to the value of x. When y = 42, x = 6. What is the value of y when x = 9? 45, 28, 63, 252

Answer 1

$y=28$

1) We know that an inversely proportional variation can be written as:

$y=k(\frac{1}{x})$

2) Note that we were also told that when y= 42, x=6 so let's find the quantity of k:

$\begin{gathered} y=k(\frac{1}{x}) \\ 42=k(\frac{1}{6}) \\ 42=\frac{k}{6} \\ k=252 \end{gathered}$

2.2) Now, let's find the quantity of y when x=9:

$\begin{gathered} y=k(\frac{1}{x}) \\ y=252\cdot(\frac{1}{9}) \\ y=28 \end{gathered}$

Thus, the answer is y=28